A black tea is a fermented tea, differently from a non-fermented tea such as a green tea, and thus has different components and features from those of a green tea and the like. For example, catechins, which are largely contained in a green tea, go through polymerization by oxidation action from fermentation, whereby to produce theaflavin (orange color pigment and astringent taste) and thearubigin (red pigment). In addition, components called proanthocyanidin polymers form astringent taste and bitter taste, and along with added theanine (sweetness and deliciousness) and caffeine, form unique tastes of a black tea.
A fruit-juice-containing black tea beverage in which fruit juice is added to a black tea, has been preferred and drunk from the past due to appropriate astringent taste from a black tea and refreshing feeling from fruit juice or acidic ingredients.
However, such fruit-juice-containing black tea beverage has problems such that time deterioration, for example, convergent taste strongly sensed after long time storage, or browning and the like, occurs easily in accordance with interaction between components of the black tea and the components of the fruit juice.
Therefore, in the past, in order to suppress such time deterioration, a method has been adopted of alleviating the astringent taste or suppressing turbidity or precipitation by reducing the amount of fruit juice added to a black tea beverage, or performing tannase treatment for an extraction liquid of black tea, or performing chlorogenic acid esterase treatment for fruit juice added to a black tea (for example, see Patent Document 1).